Precipitating silver halide in 0.5 to 3 percent weight aqueous gelatin solution

ABSTRACT

A method for producing a sensitive material with silver halide giving directly a positive image by exposing the sensitive material to the light to throw a desired image on it and then developing it by conventional method.

United States Patent lnventor Tatsuro Matsuo 2-772, Shimotakaido, Suginami-ku, Tokyo, Japan Appl. No. 806,377

Filed Mar. 12, 1969 Patented Nov. 16, 1971 Assignee Kabrishiki Kaisha Ricoh, Ota-ku, Tokyo,

Japan,

PRECIPITATING SILVER HALIDE IN 0.5 T0 3 PERCENT WEIGHT AQUEOUS GELATIN SOLUTION 1 Claim, 1 Drawing Fig.

US. Cl 96/ll4.7, 96/64 Int. Cl G03c l/72 Field of Search 96/] 14.7, 64

[56] References Cited UNITED STATES PATENTS 2,717,833 9/1955 Wark 96/64 X 3,137,576 6/1964 Himmelmann et al 96/1 14.7 3,153,593 10/1964 De Pauw 96/1 14.7 3,314,796 4/1967 Gotze et a] 96/64 X OTHER REFERENCES Zelikman et 211.: Making and Coating Photographic Emulsions, pp. 19- 22 and 119, the Focal Press, New York (1964) Primary Examiner-Norman G. Torchin Assistant Examiner-Won H. Louie, .lr. Attorney-Burgess, Ryan and Wayne ABSTRACT: A method for producing a sensitive material with silver halide giving directly a positive image by exposing the sensitive material to the light to throw a desired image on it and then developing it by conventional method.

PATENTEDNUV 16 l97| INVENT OR ATTORNEYS PRECIPITATING SILVER HALIDE IN 0.5 T 3 PERCENT WEIGHT AQUEOUS GIELATIN SOLUTION BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a sensitive material with silver halide presenting reversal effect, i.e. phenomenon of solarization, said sensitive material having a sensitive layer, which has been formed of an emulsion of silver halide dispersed in an aqueous solution containing less than 3 percent by weight of gelation, on the supporter.

2. Description of the Prior Art Conventional sensitive materials for reversal development have been made by steps of: preparing an emulsion of silver halide by dispersing it in an aqueous solution of 4-10 percent by weight of gelatin, ripening the emulsion at a temperature of 40 C. to boiling point for l2 hours, coating the ripened emulsion onto the supporter, gelating the emulsion by rapidly cooling the coated supporter to 0 C. and drying the gelated emulsion at 0 C. to 40 C. by cold dry air to prevent melting of the gel. The sensitive materials thus obtained, however, dont present the good reversal effect when subjected to exposure to the light.

Therefore, it is an object of the present invention to provide an improved sensitive material giving the good reversal effect, namely indicating the high degree of solarization when subjected to exposure to the light.

SUMMARY OF THE INVENTION The present invention relates to a method for producing an improved sensitive material with silver halide presenting good reversal effect.

A method for producing a sensitive material of the present invention comprises the steps of: preparing an emulsion by dispersing silver halide in an aqueous solution containing less than 3 percent by weight of gelatin, ripening the emulsion at a temperature of 50 C. to boiling point of the emulsion, coating the ripened emulsion onto the supporter and then immediately drying the coated supporter by hot air having a temperature of 50 C. to 140 C. The sensitive material thus obtained presents the high degree of solarization, that is to say, the high reversal effect, when subjected to exposure to the light. When the content in the aqueous solution of gelatin is more than 3 percent, in proportion as the content of gelatin increases, the drying of the coated supporter by hot air becomes more difficult, and the reversal effect is reduced.

The appended drawing shows the curves of solarization portion indicating the relation of the amount of exposure (E) and the density of the image (D). E is the product of lux (IX) and second (s), and D is measured by densitometer. The curves 1, 2, 3, 4, 5 and 6 are those obtained from the sensitive materials which have been made of the emulsion prepared by dispersing DESCRIPTION OF THE PREFERRED EMBODIMENTS The nonlimitative preferred embodiments are shown in following:

Example I A-solution:

distilled water 300cc. Nl-LBr 24 KI lg. KC] lOg.

The processes of the present invention should be carried out in a dark place. Each of A-, B-, C- and D- solutions is prepared by dissolving each of said components into the distilled water.

B-solution is added to A-solution and the mixture thus obtained is kept at 75 Cjand C-solution is added into said mixture within 5 minutes and then this mixture is stirred at 75 C. for l hour (first ripening). In this case, the concentration of gelatin in the solution should be less than 3 percent by weight.

In order to remove products other than silver halide, which has been produced by reacting silver nitrate with halide, said mixture of A-, B- and C-solution is washed with water through a semipermeable membrane (i.e. by dialysis). Alternatively, D-solution is added to said mixture, and after the mixture thus obtained is cooled to solidify, it it cut to slice and washed with running water for 2 hours. (In this case, the concentration of gelatin becomes less than 3 percent by absorption of water.)

The washed mixture is then heated and stirred at 75 C. for 1 hour to ripen (the second ripening). The mixture thus ripened (i.e. photographic emulsion) is coated onto the supporter (e.g. paper or film etc.), and the coated supporter is dried up by hot air of above 50 C.

The sensitive material thus obtained provides directly a dense positive image by exposing it to the light to throw a desired image on it and then developing it by conventional method.

Example 2 The photographic emulsion prepared by the method recited in the example 1, also may be applied to the production of color sensitive materials with silver halide presenting reversal effect (color positive film i.e. color transparency and color positive printing paper).

A method for producing the color positive printing paper is illustrated as an example in following.

Said printing paper comprises three layers of the top-, middle and bottom-layer and each of the layers consists of following components.

Top luyer Middle-layer Bottom-layer photographic emulsion l,000g. l,000g. LOOOg. sensitizing dye 20cc. 20cc. (0.1%) alcoholic solution) coupler 150cc. 150cc. 200cc. (5%) alcoholic solution) thickness of layer 3 3 4 Said photographic emulsion is that prepared according to example I. Said sensitizing dyes are e.g. erythrosine for the middle-layer and 3.3-diethyl-4,5;4'5'-dibenzothiacarbocyanine bromide for the bottom-layer, and couplers are terephthalyl diacetanilide, l-(3 '-sulfopheryl )-3 3- stearylaminophenyl)5-pyrazolone and 3,5-di(phenylamino)- phenol for the top-, middleand bottom-layer respectively.

l,000 g. of the photographic emulsion, which has been prepared according to example 1, is mixed with 20 cc. of 0.1 percent alcoholic solution of the sensitizing dye (3,3-diethyl- 4,5;4,5-dibenzothiacarbocyanine bromide) at about 30 C. After stirring the mixture for about 30 minutes, 200 cc. of 5 percent alcoholic solution of the coupler (3,5-di(phenylamino)-phenol) is added to said mixture and the agitation is continued for 20 minutes. The mixture (emulsion) thus obtained is coated onto the paper and dried up by hot air of about C. Thus, the paper having the bottom-layer of the thickness of 4p. when dried is obtained. Then, the gelatinous solution of the red colloidal silver is coated on the bottomlayer and dried by hot air of about 80 C. to provide a filter layer of the thickness of 1;; when dried. Said filter layer also acts as an interposed layer separating the middle-layer from the bottom-layer. The middleand the top-layer are formed in the same manner as the formation of the bottom-layer. The filter layer, which comprises yellow colloidal silver and has the thickness of 1p and acts as a separating layer, is formed between the middle-layer and the top-layer, and the protective layer consisting of gelatin is formed on the top-layer.

The color positive film also may be produced in the same manner as the production of the color positive printing paper except that an antihalation backing layer is formed on the opposite surface of the film base.

The color sensitive materials (the color positive film and the color positive printing paper) thus produced provide directly a said emulsion to cool, ripening again the emulsion by heating to a temperature of 50 C. to the boiling point of the emulsion, coating said emulsion onto a supporter and then immediately thereafter drying said supporter by hot air having a temperature of 50 to C. 

